Electrical fluid tester



May 30, 1933. 1. AN 1,912,188

ELECTRICAL FLUID TESTER Fi led April 2, 1930 Fig. 1

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IPMMMMM Ill-MUM Inventor Geo. I. Gann Patented 154.. 30, 1933 UNITED STATES GIDRGE I. GANN, 01'

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My invention relates to apparatus for testing the chemical content of a fluid by measuring the resistance offered by such fluid to the assage through it of an electrical current.

he specific form of apparatus shown and described is particularly adapted to determine the -proportion of soda ash or similar chemicals contained in steam boiler water. Such chemicals are introduced into the feed water of steam boilers in the form of boiler compounds to prevent the formation of scale in the boiler. When, due to concentration owing to evaporation, the proportion of the chemicals becomes too high the objectionable condition known as foaming results. Testing devices of the type to which the present invention relates, are used to determine such concentration so that the overcharged water 7 may be blown ofi before the condition of foaming is actually produced. Such testing devices are subject to two sources of error; one resulting from change in conductivity of the fluid due to changes in the temperature, and the other resulting from variation in the voltage of the battery or other source of current supply.

The object of my invention is to produce a testing device in which errors of the kind above referred to will be eliminated so that its indications will be dependent only on variation in conductivity of the fluid tested, due to the chemical composition of such fluid.v

In the accompanying drawing, which illustrates one form of testing device made in accordance with-my invention, Figure 1 is' a diagrammatic view of the device together with a sectional view of a portion of a steam boiler to which the same is applied; Figure 2 is a diagrammatic view showin means for rocking the central electrode or one of the terminal plugs; Figure 3 is a side view of such plug; Figure l is a section taken on the line 4-4: of Figure 3; and Figure 5 is a longitudinal section through the other terminal plug. 1

ln carrying out my invention ll employ two electrical measuring instruments, one comprising an arm or pointer 6 and actuating solenoid 7, and the other a pointer 8 and actua ting solenoid 9. The two pointers move'on 1980. Serial No. 441,160.

the same pivot 10 and cooperate with a common scale 11. The solenoids are 'soarranged that increase in the current passing through them moves the pointers in the same direction. Both solenoids are supplied with current from .a battery 12, or othercommon source of Solenoid 7 and battery 12 are connected by a circuit 13 which also includes a resistance element in the form of a terminal plug 14 extending through the wall of a steam boiler 15, the water in which is to be tested. The shell of the plug 14 constitutes one electrode and a central cyllindrical rod 16 the other electrode ofthe resistance element. Rod 16 is provided with threads snugly fittingcorresponding threads in the interior of an insulating core 17. Adjacent to the inner 'end'ot the pl a segmental portion of both the core-and he casing is cut away, as shown in Figures 3 and 4, so as to provide a ll-shaped trough or gap 18 and expose a portion only of the riphery of e rod 16. Some of the water in the boiler will enter the gap 18 forming part of the circuitthroh solenoid 7 so that its. conductivity will uene the amount of deflection of the pointer 6 when current from the battery ows through the circuit.

fiediment from the boiler water is liable to be deposited onthe exposed portion of the rod 16. To remove such sediment before a reading is taken a rocking motion is imparted to the rod l6 to cause the edges of the core 17 to scrape ofi such deposit. Such rocking movement may be imparted manually by means of an arm l9. ln order, however, to enable remote operation ll provide a solenoid 20 for movir the arm in one direction; it being returne un release of the pull of the solenoid by a spr 21. t1 solenoid may be supplied from any source at electric current but is preferably included in a circuit 22 shunted around the battery 12 and containing a switch 23 for ma m and breingthe circuit.

. Solenoid 9 is contained in a circuit 24 in multiple with the circuit ldand includin a resistance element in the form of a termina ug 25 projectingthrou boiler 15. The shell of v plug forms one hill h the wall of the 1m electrode of the resistance element, the other being formed of a threaded rod 26 extendin through an insulating core 27. The inner en of the plug 25, which is preferably in the form of a removable cap 28, is hollow and contains a resistance liquid 29 bridging the electrodes. The liquid- 29 may be any liquid varying in conductivity under the influence of temperature in the same manner as the liquid in the boiler. However, I prefer to use a portion of the boiler water itself containing the normal percentage of boiler compound. This liquid, being isolated from the oiler water, will remain constant in chemical content and its conductivity will vary only by reason of the variation in temperature of the boiler water by which it is surrounded. By rotating the threaded rod 26 its end may be causedto project a greater or less distance beyond the core 27 to adjust the resistance of the element 25 to that of the element 14 when immersed in boiler water contain-- ing the normal amount ofboiler compound after which no further movement of the rod is necessary. A switch 30 is located at such point in the line wire as to control both the circuit 13 and the circuit 24.

In using my device to test the condition of the water the rod 16 is given a rocking movement to clean the part of the rod exposed to the boiler water from sediment. As above explained, this may either be accom plished manually or electrically through the opening and closing of the switch 23. The

switch 30 is now closed, causing current from the battery to flow through solenoids 7 and '9, moving pointers 6 and 8 both in clockwise direction. If the amount of boiler compound the water in the boiler is normal, both pointers will be moved an equal distance so that while their position is changed their angular relation will remain the same and consequently the number of included divisions on the scale .11 will be constant.

Changes in temperature will cause variation in the amount of movement but will not change the angular: relatioifiof the pointers as they will cause equal variety in the conductivity of both resistance elements. The same is true of variations in the voltages of the batte which will afiect both instruments alike an while changing the amount of movement of the pointers, will not vary their angular relation. en, however, the percentage of boiler compound in the boiler water increases, the conductivity of the resistance element 14 will be increased without any corresponding increase in the conductivity of the resistance element 25, so that the pointer 6 will be moved 'a greater distance than the pointer 8 and their angularseparation lessened with consequent decrease in the number of included divisions on the scale 11. When the decrease on the scale reading has reached a predetermined amount, preferably ,terial having an openin exposing a when the pointers, coincide, the attendant will be warned that the point of foaming has been reached and that the chemically overchar ed water must be blown off.

While I have shown and described a construction in which the pointers of the two instruments have the same pivot and cooperate with a common scale, any means, mechanical or otherwise, may be used to integrate the movement of the instruments so that the indication will be their resultant.

Having fully described my invention, what I claim as new and desire to secure byLetters Patent of the United States is 1. In a device for testing liquids, an electrode consistin of a conducting rod surrounded by a body of insulating material, and means for causing relative movement between said rod and body to remove deposits from the former.

2. In a device for testing liquids, an electrode consistin 'of a cylindrical conducting rod surrounde by a body of insulating martion only of the periphery o the rod, an means for causing relative rotar movement between the rod and the ho y to remove deposits from the former.

3. In a devicefor testing liquids, an electrode consisting of a cylindrical conducting rod threaded into a body of insulating material, said body being provided with an opening exposing a portion only of the periphery of the rod, and means for imparting .a rocking movement to the rod to remove 

